The objective of the proposed research is the investigation of the noradrenergic cyclic AMP generating system in limbic structures of the brain and the elucidation of its role in the mode of action of major psychotropic drugs. We are particularly interested to study how prolonged administration of antidepressants, antipsychotic drugs and CNS stimulants changes the sensitivity of this system. We attempt to determine the molecular consequences of drug induced adaptive changes in the system by studying both in vitro and in vivo phosphorylation of membrane and other proteins in limbic brain tissue. It is our hope that these studies will shed light on the molecular pharmacology of major psychotropic drugs and will contribute to a better understanding of their therapeutic mode of action and to improved pharmacotherapy of mental illness.